1. Field of the Invention
This invention relates to diesel fuel additives, and more particularly to a composition of certain nitrogen-containing compounds and a method of its use in diesel fuel to impart improved properties.
2. Description of the Related Art
W. German Patent Application S 34337 IVC/23b (DE OS 960,920) (Socony Mobil Oil Company) describes certain distilled fuels containing linear aliphatic primary monoamines having 7 to 18 carbon atoms per molecule. These fuels may be fuel oils, gasoline, etc., e.g. heating oils or diesel oils. Such oils are described as having a tendency on storage to form precipitates or sludge and hence to block sieves or filters, and the reason for including the above monoamines in them is to prevent the blockage of sieves or filters. Tests described in the examples employ an oil having a boiling range between 160.degree. and 340.degree. C., and 75 g per cubic meter of amine, pumped through a 100-mesh Monelmetal sieve. The amines illustrated include octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and various mixtures of amines.
German Patent 659,210 (I.G. Farbenindustrie) discloses motor fuel, e.g. benzole, gasoline, containing water-insoluble aliphatic or aliphatic-aromatic amines having a straight chain of atoms, as corrosion inhibitors against the effects of sulphuric acid produced in the engine from organic sulphur impurities in the fuel. Although n-octylamine, dodecylamine and octadecylamine are specifically named, the sole example comprises 100 parts by weight of gasoline together with 1 part by weight of dimethyldodecylamine.
U.S. Pat. No. 4,509,952 (filed Apr. 1, 1981), assigned to Ethyl Corporation, discloses fuel oil compositions comprising furnace oil or diesel oil and alkyldimethylamine (a C.sub.4-20 n-alkyl dimethylamine, preferably a C.sub.8-14 n-alkyl dimethylamine) wherein the amine is included in order to stabilise the oil against deterioration, e.g. colour deterioration, sludge formation, filter plugging, emulsification and rusting of storage containers. N,N-dimethyl dodecylamine is sold by Ethyl Corporation under trade mark "ADMA 12".
U.S. Pat. No. 3,707,362 (filed Dec. 26, 1972), assigned to Esso Research and Engineering, discloses fuel, particularly gasoline, consisting of a major proportion of volatile hydrocarbons and a minor proportion of a tertiary aliphatic amine with a C.sub.12-20 n-alkyl substituent and two C.sub.1-3 alkyl substituents, preferably together with a C.sub.12-20 n-alkyl primary amine. The amine/amine mixture is stated to improve the distribution of air-fuel mixture in the induction system, and hence to the cylinders, of an internal combustion engine and to reduce the tendency of a film of liquid to form on the walls of the inlet manifold of the engine. Tests and comparative tests describe use of gasolines containing, variously, tertiary amines, primary amines and mixtures of such amines.
U.S. Pat. No. 4,482,357 (filed Dec. 30, 1983), assigned to Ethyl Corporation, discloses a distillate fuel for indirect compression ignition (diesel) engines which includes (i) a hydrocarbyl-substituted succinimide or succinamide, (ii) a C.sub.8-60' N.sub.1-10 hydrocarbyl amine, and (iii) N,N'-disalicylidene-1,2-diaminopropane. The combination of additives (i) to (iii) is stated to minimize coking on the injector nozzles. In the combination of additives (i) to (iii), (ii) is preferably a C.sub.8-18' more preferably C.sub.12-16' tertiary-alkyl primary amine.
It has now surprisingly been found that use of certain nitrogen-containing compounds in diesel fuel per se reduces fouling of injectors in diesel engines. This reduced fouling is an entirely different technological effect from the prevention of blockage of sieves or filters described in DE OS 960,920 discussed above, since the diesel fuel reaching the cylinders of a diesel engine will already have passed a fine filter, and the fouling of injectors is induced by the high temperatures to which the injectors are exposed in operation of the engine.